It's a move you'd only see in fan fiction or mods for the PC version of Street Fighter, so... the fact this is a mod for the PC version of Street Fighter x Tekken probably explains things.

It's just one of a series of great mods that have been under the spotlight this past week, some for SFxT, others for Super Street Fighter IV Arcade Edition. In the gallery above you'll see other examples, like Dr. Doom replacing Sagat and Shinobi replacing Ken.